Question

In my app I am using the camera and photo library to get an UIImage,
this UIImage is then scaled down about 20 times its normal size
I then set a NSData object based off the UIImage.

_regularImage = [self resizeImage:_takenImage width:100 height:100];


-(UIImage *)resizeImage:(UIImage *)anImage width:(int)width height:(int)height
{

    CGImageRef imageRef = [anImage CGImage];

    CGImageAlphaInfo alphaInfo = CGImageGetAlphaInfo(imageRef);

    if (alphaInfo == kCGImageAlphaNone)
        alphaInfo = kCGImageAlphaNoneSkipLast;


    CGContextRef bitmap = CGBitmapContextCreate(NULL, width, height, CGImageGetBitsPerComponent(imageRef), 4 * width, CGImageGetColorSpace(imageRef), alphaInfo);

    CGContextDrawImage(bitmap, CGRectMake(0, 0, width, height), imageRef);

    CGImageRef ref = CGBitmapContextCreateImage(bitmap);
    UIImage *result = [UIImage imageWithCGImage:ref];

    CGContextRelease(bitmap);
    CGImageRelease(ref);

    return result;      
}

NSData *image1Data = UIImageJPEGRepresentation(_regularImage, 1);

I cant seem to figure anything else out that might cause this

Thank you

LittleRy

Answer 1

The issue here may be that you are creating your bitmap context or UIImage in the wrong way. Try debugging and checking if _regularImage is nil, or if it’s invalid. For scaling an image, I would suggest using a third party library called ANImageBitmapRep. It’s a small set of classes that allows for easy cropping, resizing, rotating, etc of images on the iPhone. Scaling a UIImage can be done like this:

ANImageBitmapRep * irep = [ANImageBitmapRep imageBitmapRepWithImage:myImage];
[irep setSize:BMPointMake(myWidth, myHeight)]; // scale the image
UIImage * theImage = [irep image];
[irep release];
NSData * jpeg = UIImageJPEGRepresentation(theImage, 1);

With this sort of code I doubt that UIImageJPEGRepresentation would be the issue. The ANImageBitmapRep class itself handles the CGContextRef stuff internally, making your job very much easier.